Process of producing sound records



Patented Feb. 1% rest wh m BE TATEifi more rear erases benindustrie Ahtiengeselischait, Franhiort-onthe-Ma n, Germany No Drawing. Application January 11, 1938, 8e-

riai No. M4398. 193? ifiiaim- Our invention relates to a method of making sound records. I

For a long time great endeavours have been made towards removing the well known tendaring of sound records. It is true that cellulosic derivatives and various polyvinyl condensation products yield tenacious records which are resist-ant to fracture, but such records have met with little approval on account of their soft- 10 ness. The hard phenolic resins and the hitherto known carbamide resins are hardened too slowly when pressed and therefore adhere to the mould,

Our present invention comprises the application for the manufacture of sound records of new resins obtained by condensing compounds containing pent-avalent or hexavalent heterocyclic rings in which the group -N=c-Nn-x x=n or NIL) 2o 1 is present at least twice. with low molecular aliphatic aldehydes, particularly formaldehyde or agents setting free formaldehyde. The application of such resins allows oi the menufacture of unobjectionable records. The new resins have moreover the advantage of yielding light coloured discs which are fast to light. As suitable resins there may be mentioned those obtained by condensing formaldehyde with. mel- 3 amine, ammellne, benzos'uanamine, 2.4.6-tri- .any supporter.

in Germany sane-arr 18,

(Cl. Slit-70) aminopyrimidine, Z-mercapto pyrimidine, 2.3- and 2.4-diaminoquinazoline, Le-diamimphthalazine, cyanuric trihydraaide, guanazole, phenyl g-uana'zole, and the like.

Papers which have been impregnated or coated 5 with such resins can be worked up with an extraordinary rapidity to solid records, when pressed in the hot in the usual mould.

In order to obtain any desired thickness of the plate a plurality of impregnated papers may it) be arranged in layers. As basic material other substances, such as pasteboard, wood, sheetmetal and the like may be used and the resin may be laid thereon in a pure form. without essai'y but if only the good capacity of the said resins for being pressed comes into consideratlon. powdered supporters may be added to the resins such as cotton, wood-dust, slate-dust, lamp black and the like.

We claim: A process of producing sound records which comprises coating paper with a resin consisting of the condensation product of melamine with formaldehyde and hot pressing the resultin 25 coated paper.

WERNER ZERWECK. KARL KELLER. PETER PINTEN.

If no particular rigidity is nee- 15 v 

